The present invention relates to an apparatus for breaking pavement, and more specifically, to an elongated leaf spring pack having an impact tool on one end with a whipping action being imparted to the tool.
Highway programs are changing from new construction to rehabilitation of existing streets and highways. A common rehabilitation technique for concrete pavements is to overlay the concrete with a hot mix asphalt. However, a serious problem which develops in most overlays is reflective cracking.
Reflection cracking is the propagation of existing cracks and joints in the concrete pavement upwards through the resurfacing layer. The cracking of the overlay is primarily caused by stresses that develop at the bottom of the new overlay directly over the existing cracks and joints in the concrete. The new overlay is usually bonded to the concrete pavement and as the concrete pavement expands and contracts with changing temperatures, stresses develop in the new overlay due to joint movement and reflective cracking develops.
Certain techniques have been developed to reduce reflection cracking including the addition of welded wire mesh and fiber fabric reinforcing to the asphalt overlay, use of lower viscosity asphalt cements, and use of asphalt rubber cements. Another technique which has received considerable attention is to control the reflection cracking by breaking the existing concrete pavement into small segments before overlaying with the asphalt. This construction procedure includes cracking the concrete slabs into pieces small enough to significantly reduce joint movement, rolling the pieces with a roller to seat the pieces firmly on the base or subgrade, and then overlaying with asphalt.
Cracking and seating concrete pavements before overlaying with the hot mix asphalt has many advantages over other methods for controlling reflection cracking. However, the available construction equipment for cracking concrete pavement to specification is limited (e.g., U.S. Pat. Nos. 3,133,730 and 3,181,627 to Cornett). It is important to control the size of the cracked or fractured concrete pavement pieces and to crack the concrete by fracturing it without distorting the surface. This is desirable to retain as much of the aggregate interlock or bridge strength of the concrete as possible.
Thus, it is a principal object of the present invention to provide an apparatus for breaking pavement which has the ability to vary the impact force as required for fracturing the concrete. Further, the present invention permits sizing of the cracked pattern to specification without distorting the concrete, thereby retaining as much aggregate interlock or bridge strength from the concrete as possible.